[hider=Half-Elves]
Humans and elves are capable of interbreeding, siring a half-elf. Albeit 9 out of 10 such pregnancies generally result in a miscarriage and may even threaten the mother's life. There are several complications like the half-elven child being too much of a burden on an elven mother or in reverse the child requiring and producing chemicals which the human mother doesn't have. Yet scientists found out these problems are minor compared to what came down to simple compatibility. A percentage of elven population and a percentage of human population are capable of successfully siring an offspring. Even among them there are people with high chance of conceiving a halfbreed and those who may succeed but the risks are higher. Studies show there's no clear cutoff line. Since genetics are only at the developing stage Yllendthyr has no known means to identify an "ideal mate" neither the current government is interested in such research.

That is because the topic of half-elves is a sorts of taboo. Officially no half-elves exist in Yllendthyr. They're either classified as humans or elves within the records. Half-elves of noble birth retain their status while others are considered the same as humans. if not worse. Half-elves of low status are outcasts, often shunned by both humans and elves alike. Albeit there's a certain way to change that. Half-elves who marry into noble families or otherwise gain fame or higher status can earn the right to become "honorary elves" thus jumping straight up on the social ladder. As such many half-elves pursue military career and they're often rather good at it. Half-elves can randomly inherit the abilities of both elves and humans, they're a mosaic race of both. As such it's possible for a half-elf to inherit a human's strong physique along with the senses and physiology of his elven ancestor, albeit certainly not the norm. Half-elven lifespan is difficult to determine. In general it lies somewhere between that of a human and elf. Although it worths noting that their mixed genes make half-elves susceptible to some quite dangerous genetic disorders.
[/hider]
Well, there's at least one pair of races who'll be capable of that.

[quote=@ZB1996]
<Snipped quote by Willy Vereb>

I'd like there to be there to be interbreeding. Interspecies romance/marriage will eventually become a major domestic issue in my nation, although it will probably be outside the timeline of this RP before this is realized to any meaningful extent.
[/quote]